Mercurial > hg > audiostuff

comparison spandsp-0.0.3/spandsp-0.0.3/src/spandsp/time_scale.h @ 5:f762bf195c4b

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
import spandsp-0.0.3
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 16:00:21 +0200
parents
children
comparison
equal deleted inserted replaced
4:26cd8f1ef0b1 5:f762bf195c4b
1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * time_scale.h - Time scaling for linear speech data
5 *
6 * Written by Steve Underwood <steveu@coppice.org>
7 *
8 * Copyright (C) 2004 Steve Underwood
9 *
10 * All rights reserved.
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2, as
14 * published by the Free Software Foundation.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 *
25 * $Id: time_scale.h,v 1.7 2006/10/24 13:45:28 steveu Exp $
26 */
27
28 #if !defined(_TIME_SCALE_H_)
29 #define _TIME_SCALE_H_
30
31 /*! \page time_scale_page Time scaling speech
32 \section time_scale_page_sec_1 What does it do?
33 The time scaling module allows speech files to be played back at a
34 different speed, from the speed at which they were recorded. If this
35 were done by simply speeding up or slowing down replay, the pitch of
36 the voice would change, and sound very odd. This modules keeps the pitch
37 of the voice normal.
38
39 \section time_scale_page_sec_2 How does it work?
40 The time scaling module is based on the Pointer Interval Controlled
41 OverLap and Add (PICOLA) method, developed by Morita Naotaka.
42 Mikio Ikeda has an excellent web page on this subject at
43 http://keizai.yokkaichi-u.ac.jp/~ikeda/research/picola.html
44 There is also working code there. This implementation uses
45 exactly the same algorithms, but the code is a complete rewrite.
46 Mikio's code batch processes files. This version works incrementally
47 on streams, and allows multiple streams to be processed concurrently.
48 */
49
50 #define TIME_SCALE_MIN_PITCH 60
51 #define TIME_SCALE_MAX_PITCH 250
52 #define TIME_SCALE_BUF_LEN (2*SAMPLE_RATE/TIME_SCALE_MIN_PITCH)
53
54 typedef struct
55 {
56 double rate;
57 double rcomp;
58 double rate_nudge;
59 int fill;
60 int lcp;
61 int16_t buf[TIME_SCALE_BUF_LEN];
62 } time_scale_t;
63
64 #ifdef __cplusplus
65 extern "C" {
66 #endif
67
68 /*! Initialise a time scale context. This must be called before the first
69 use of the context, to initialise its contents.
70 \brief Initialise a time scale context.
71 \param s The time scale context.
72 \param rate The ratio between the output speed and the input speed.
73 \return 0 if initialised OK, else -1. */
74 int time_scale_init(time_scale_t *s, float rate);
75
76 /*! Change the time scale rate.
77 \brief Change the time scale rate.
78 \param s The time scale context.
79 \param rate The ratio between the output speed and the input speed.
80 \return 0 if changed OK, else -1. */
81 int time_scale_rate(time_scale_t *s, float rate);
82
83 /*! Time scale a chunk of audio samples.
84 \brief Time scale a chunk of audio samples.
85 \param s The time sclae context.
86 \param out The output audio sample buffer.
87 \param in The input audio sample buffer.
88 \param len The number of input samples.
89 \return The number of output samples.
90 */
91 int time_scale(time_scale_t *s, int16_t out[], int16_t in[], int len);
92
93 #ifdef __cplusplus
94 }
95 #endif
96
97 #endif
98 /*- End of file ------------------------------------------------------------*/

Repositories maintained by Peter Meerwald, pmeerw@pmeerw.net.